<dependency>
  <groupId>com.an.otpview</groupId>
  <artifactId>otpview</artifactId>
  <version>0.1.0</version>
  <type>pom</type>
</dependency>

xmlns:app="http://schemas.android.com/apk/res-auto"

.....
       <com.an.otpview
            android:id="@+id/otp_view"
            app:background_color="@android/color/black"
            android:inputType="number"
            app:otp_maxLength="1"
            app:otp_gravity="center"
            app:otp_textColor="@android:color/white"
            app:otp_textSize="@dimen/font_large"
            android:orientation="horizontal"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
.....